Influence of Hydrolysis Time on Properties of SiO2 Aerogels Prepared by Ambient Pressure Drying

Abstract

With ethyl orthosilicate as precursor and trimethylchlorosilane as surface modifier, hydrophobic SiO2 aerogels are prepared through sol–gel process combined with ambient pressure drying process. The influence law of different hydrolysis times on microstructure and physicochemical properties of aerogels when the reaction precursor is in the sol phase is studied. The results show that the hydrolysis time increases from 6 to 36 h, and the prepared aerogels have nanoscale mesoporous structure and hydrophobic properties. With the increase in hydrolysis time, the porosity and specific surface area of the samples increase and then decrease, and the density decreases and then increases, all of which reach their peaks at 18 h. The properties of samples are optimal after being hydrolyzed for 18 h. The prosperity is 96%, specific area is 1539.7706 m2/g, the density is 0.08921 g/cm3, and the contact angle is 148.3°.